The objectives of this pilot project are to evaluate changes in ovarian morphology, serum estrogen, bone density, and DNA deletions over time in female rhesus monkeys. Preliminary results indicate that bone strength from young monkeys 3-5 years of age and aged monkeys 22-25 years is different and that breaking strength of femurs decreases substantially with age. Young monkey femur strength was 13.5 MPa (comparable to a previous report by Yamada, 1970) while aged monkey femur strength averaged 9.7 MPa, about 70% less. Thickness of cortical and trabecular bone decrease with age while the number of trabecular intersections increases. Similar measurements using the wing of the pelvis (iliem) failed to demonstrate these correlations. Recent work has concentrated on development of more sensitive measurements of bone strength. Precisely machined specimens of femur and lumbar vertebrae have recently been tested by ash content, ultrasonic mapping, compression and three point bending tests usin g a mechanical testing system (MTS Systems Corporation, Minneapolis). Using a three-point bending test on specimens from the femur the average ultimate strength in the oldest age group (25-30 yr.) was significantly lower (p<0.05) than in all other age groups except the youngest (0-5 yr.)(p=0.076). We plan to evaluate the effect of activity level and age on bone strength (using housing history of coral vs. inside cage) but as yet, we do not have enough specimens to make this comparison. Using ultasonic equipment (digitizing oscilloscope, function generator, and piezoelectric crystal transducers) density tends to be less in older femur groups while elastic moduli (a measure of bone strength) peak at age 15 (11.9 Gpa). Young animals and very old animals have very similar elastic moduli (4.6 and 5.3 Gpa, respectively). A significant relationship has been established between ash density and compressive strength of lumbar bone but no significant difference amoung age groups and ultimate s trength measurements (range 8.3-11.1 Mpa). Enumeration of eggs, primary follicles and cystic follicles in histologic sections of ovaries showed substantial decreases with age. The results could provide the basis for future studies on effects of aging in females from puberty through menopause in response to exercise and dietary treatments. FUNDING Base Grant, Venture Research PUBLICATIONS None